error on pagination edge cases (#26190)

if you do the following in a UDF, you can cause a system error loop with an error message about the cursor not being set.

```
await ctx.db.query("messages").paginate({
      ...args.paginationOpts,
      maximumRowsRead: 0,
      // or maximumBytesRead: 0,
} as PaginationOptions);
```

fix this by catching the zero case early.

and also detect when we hit a pagination limit before setting the cursor. this should never happen, because in order to hit a pagination limit you need to have fetched some data, and if you fetched data then you must have set the cursor. if the scenario ever does happen, we can log the pagination error, which should help narrow down what's going on.

GitOrigin-RevId: 491bceae908bce0c6812378e3c160de3c303983d

Author: ldanilek

crates/isolate/src/environment/udf/async_syscall.rs

@@ -1006,6 +1006,14 @@ impl<RT: Runtime, P: AsyncSyscallProvider<RT>> DatabaseSyscallsShared<RT, P> {
                 Err(e) => {
                     if e.is_pagination_limit() {
                         page_status = Some(QueryPageStatus::SplitRequired);
+                        if query.cursor().is_none() {
+                            // Intentionally drop ErrorMetadata because this should
+                            // be impossible, so we want to throw a system error instead.
+                            anyhow::bail!(
+                                "This should be impossible. Hit pagination limit before setting \
+                                 query cursor: {e:?}"
+                            );
+                        }
                         break;
                     }
                     anyhow::bail!(e);
@@ -1060,6 +1068,12 @@ impl<RT: Runtime, P: AsyncSyscallProvider<RT>> DatabaseSyscallsShared<RT, P> {
                 "Must request at least 1 document while paginating"
             ));
         }
+        if args.maximum_rows_read == Some(0) || args.maximum_bytes_read == Some(0) {
+            anyhow::bail!(ErrorMetadata::bad_request(
+                "InvalidPaginationLimit",
+                "maximumRowsRead and maximumBytesRead must be greater than 0"
+            ));
+        }
 
         let start_cursor = args
             .cursor